The subject matter disclosed herein relates generally to electrodialysis (ED) electrodes, and more particularly, a system for rinsing ED electrodes.
There are several regions in the United States (e.g., the southwestern United States including New Mexico, Southern California, and parts of Texas) and throughout the world that experience shortages in potable water supplies due, in part, to the arid climate of these geographic locales. As water supplies are limited, the need for innovative technologies and alternative water supplies for both drinking water and agriculture is important. One method for obtaining an alternative source of potable water uses desalination systems to produce the potable water.
The desalination process may involve the removal of salts from seawater, agricultural run-off water, and/or brackish ground water brines to produce potable water. Membrane-based desalination may use an assortment of filtration methods, such as nanofiltration and reverse osmosis, to separate the raw brine stream into a desalinated water stream and a tailing stream. The tailing streams may contain various salts and other materials left over after the desalination process. Included in these tailing streams may be valuable salts and minerals which may be extracted using membrane-based and/or evaporative techniques.
One such mineral extraction technique utilizes electrodialysis (ED) to facilitate ion exchange and/or the enrichment of certain minerals. However, ED and other membrane-based techniques may be susceptible to membrane oxidation and degradation due to bleach, acid, chlorine, and/or other impurities. The impurities may result from mineral deposits caused by ion leakage across the membranes and/or formed by chemical conversion in response to imbalances in the circulating pH levels of a rinse solution. In certain configurations, ED electrodes may produce byproducts, such as magnesium hydroxide, calcium hydroxide, and chlorine, which may contaminate the rinse solution and degrade the electrodes and/or deposit scale on the membranes. Calcium sulfate may also form in the electrode compartments if calcium from the process brines enters the electrode compartment and mixes with the sulfate used to maintain conductivity in the rinse solutions. Unfortunately, rinse systems may not remove impurities and/or control the pH of the rinse solution.